It is known that certain polymers form cyclic fractions during the synthesis. This is made possible by the steric flexibility and the geometrical shape of the repeat units. Poly(dimethyl siloxane) is a classic example in which cyclics occur during synthesis and can be isolated. Molecular simulations showed that polycarbonates, e.g., PC(A), PC(Z), PC(P), all have geometrical shape and stereochemical facility to form cyclics, ranging from 3 to 15 repeat units. (P. R. Sundararajan, "Possible Helical Shapes of the Polycarbonate Chain and Their Influence on the Unperturbed Dimensions," Macromolecules, Vol. 20, pp. 1534-1539 (1987)). Brunelle et al., have reported synthesis of cyclic polycarbonates, with 2-21 units (Daniel Brunelle et al., "Preparation and Polymerization of Cyclic Oligomeric Carbonates: New Route to Super-High Molecular Weight Polycarbonate: An Overview," Polym. Preprints, Vol. 30 (2), pp. 569-570 (1989); Daniel Brunelle et al., "Studies on the Mechanism of Amine-Catalyzed Cyclic Oligomeric Carbonate Formation," Makromol. Chem., Macromol. Symp., Vol. 54/55, pp. 397-412 (1992)).
Threading linear molecules into cyclic molecules to form rotaxanes has been explored as reflected in the following documents:
Harry W. Gibson et al., "Polyrotaxanes: Molecular Composites Derived by Physical Linkage of Cyclic and Linear Species," Advanced Materials, Vol. 5, No. 1, pp. 11-21 (1993);
Yu. S. Lipatov et al., "Synthesis and Structure of Macromolecular Topological Compounds," Advances in Polymer Science, Vol. 88, pp. 49-76 (1989);
Gerhard Wenz, "Cyclodextrins as Building Blocks for Supramolecular Structures and Functional Units," Angew. Chem. Int. Ed. Engl., Vol. 33, pp. 803-822 (1994);
L. Garrido et al., "Studies of cyclic and linear poly(dimethylsiloxanes): 15. Diffusion coefficients from network sorption measurements," Polymer Communications, Vol. 25, pp. 218-220 (1984);
L. Garrido et al., "Studies of Cyclic and Linear Poly(dimethylsiloxane): 16. Trapping of Cyclics Present During the End Linking of Linear Chains into Network Structures," Polymer Communications, Vol. 26, pp. 53-55 (February 1985);
S. J. Clarson et al., "Studies of cyclic and linear poly(dimethylsiloxaners): Effect of ring size on the trapping of cyclic polymers into network structures," Polymer Communications, Vol. 27, pp. 244-245 (1986);
S. J. Clarson, "Studies of Cyclic and Linear Poly(dimethylsiloxanes): 24. Topological Trapping of Cyclic Polymers into Unimodal and Bimodal Model Network Structures," Polymer Communications, Vol. 28, pp. 151-153 (May 1987); and
Fauteux et al., U.S. Pat. No. 5,538,655, having the title "Molecular Complexes for Use as Electrolyte Components."
The top surface and the bottom surface of a moving web or belt type photoreceptors may be in contact with backer bars and back cleaners inside the xerographic printing machine. Such contact abrades the surfaces of the photoreceptor and may eventually wear away enough of the photoreceptor to impair its function. Another source of wear of the top surface of a photoreceptor comes from electrochemical reaction of the corona charging devices. Abrasion resistant materials are desirable for the top and bottom surfaces of the photoreceptor to prolong its life. The present invention addresses the problem of abrasion of the photoreceptor by providing new materials with enhanced abrasion resistance for the anticurl layer, the charge transport layer, and the overcoating layer, particularly in those embodiments where there is absent an overcoating layer over the charge transport layer.
Conventional photoreceptors are disclosed in Chambers et al., U.S. Pat. No. 5,876,887; Miyamoto et al., U.S. Pat. No. 5,521,041; and Derks et al., U.S. Pat. No. 5,665,501.